Containers or cartons for the packaging and shipping of fruit are, or may be, subjected to substantial crushing loads because they are frequently stacked many cartons high. They may also be exposed to a highly humid environment to keep the contained fruit from drying out. The cartons may be kept in this humid environment for a period of months. A common corrugated paper box which may be used for this purpose has limited compressive strength, and this is severely reduced from exposure to high humidity. One technique which has been used to attempt to overcome this shortcoming is to form the end panels of the carton with three or four layers of corrugated paper. This will withstand the humid environment for a period, but such cartons, if loaded with several others on top, will ultimately crush, allowing their contents to be crushed, also. Since the traditional end panels of wood about 7/8 inch thick have become quite expensive, other materials have been investigated and tried with varying degrees of success. A carton end formed of a shell of high density plastic such as polystyrene filled with and bonded to a low-density expanded plastic material has achieved a limited degree of success, but recent increases in the cost of the plastic materials have made such panels uncompetitive with wood, at least for some applications. This structure appears in U.S. Pat. No. 3,905,478 filed in the name of Dale S. Peterson et al and assigned to the assignee of the present application. Other attempts to use some of the least expensive plastic materials have resulted in carton ends which have too much material in them, in which case they are too expensive, or they have been made with less material, frequently becoming too fragile in the process and proving to be unsuitable for the intended application.